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| Paper: |
Helioseismic Detection of Emerging Magnetic Flux |
| Volume: |
462, Progress in Solar/Stellar Physics with Helio- and Asteroseismology |
| Page: |
283 |
| Authors: |
Ilonidis, S.; Zhao, J.; Kosovichev, A. G. |
| Abstract: |
Investigating the properties of magnetic flux emergence is one of the most important problems of solar physics.
In this study we present a newly developed deep-focus time-distance
measurement scheme which is able to detect strong emerging flux events in the
deep solar interior, before the flux becomes visible on the surface. We discuss in detail the differences
between our method and previous methods, and demonstrate step-by-step how the
signal-to-noise (S/N) ratio is increased.
The method is based on detection of perturbations in acoustic phase travel times determined from cross-covariances of solar oscillations observed on the surface. We detect strong acoustic travel-time reductions of an order of 12 – 16 seconds at a depth of 42 – 75 Mm. These acoustic anomalies are detected 1 – 2 days before high peaks in the photospheric
magnetic flux rate implying that the average emerging speed is 0.3 – 0.6 km s-1. The results of this work
contribute to our understanding of solar magnetism and benefit space weather forecasting. |
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